This invention relates to a boring tool having at least two cutter elements that can be adjusted to achieve two cutting actions. During insertional movement of the tool into a hole in a work piece one (or more) of the cutter elements will machine the hole surface to a desired dimension; during retractive movement of the tool out of the hole another one of the cutter elements will perform a further machining operation, to form a precision finish hole surface. The boring tool is equipped with means for transversely adjusting the cutter elements through a fixed incremental distance when the tool is at the bottom of the hole, whereby the final hole surface has a desired degree of precision.
The invention makes use of constructions disclosed in U.S. Pat. No. 4,773,801 issued to K. G. Noggle on Sep. 27, 1988, and U.S. Pat. No. 5,193,954 issued to Carl Hunt on Mar. 16, 1993.
U.S. Pat. No. 4,773,801 discloses a boring tool wherein a relatively small diameter boring bar is joined to a larger diameter tool body by a plate that is bolted near its outer edge to an end face of the tool body. Two arcuate slots are formed through said plate a slight distance inwardly from the bolted area. These arcuate slots form two diametrically spaced neck sections that form a transverse pivot axis extending normal to the tool rotational axis.
An adjustment device is mounted on the tool body to apply a force to the plate, such that a central section of the plate can be tilted around the transverse pivot axis so as to incrementally move the cutter elements on the boring bar toward or away from the tool rotational axis. The adjustment structure is capable of achieving precise adjustments in the cutter element position, while at the same time providing a desired resistance against cutter element chatter or vibration.
U.S. Pat. No. 5,193,954 discloses a mechanism for releasably clamping a cutter element holder to a cutting machine or spindle. The mechanism comprises a housing having a frusto-conical socket for receiving a tubular section of the cutter element holder. The tubular section is releasably clamped or wedged in the socket by multiple wedge lock elements that are mounted within the housing for radial movements toward or away from an annular shoulder formed on the inner surface of the tubular section.
As the wedge lock elements move radially outwardly they abut the annual shoulder on the tubular section of the cutter element holder, thereby moving the cutter element holder further into the socket. The cutter element is thus firmly, but releasably, clamped to the cutting machine or spindle. An axially movable drawbar is provided for operating the wedge lock elements to their clamped or unclamped positions.